If I switch jobs mid-year, how does that affect my HSA contribution limit?

Your annual HSA contribution limit is set by the IRS and generally isn't cut just because you changed employers, as long as you stay covered by an HSA-eligible high-deductible health plan. You keep your HSA (it's yours, not the employer's) and can keep contributing up to the annual max across both jobs combined. Watch two things: don't let both employers' payroll contributions plus your own push you over the yearly limit, since excess contributions get penalized, and be careful if you lose HDHP coverage for part of the year, which can prorate your limit under the month-by-month rules. The last-month rule can also let you contribute a full year's amount if you're HSA-eligible on December 1, with a testing-period catch.